Thiofunctional polysiloxane fluids may be prepared by reacting a thiofunctional silane or siloxane with an organopolysiloxane in the presence of acidic clays to form thiofunctional polysiloxane polymers. These thiofunctional polymers degrade in the presence of acidic clays, especially at elevated temperatures, to form volatile, lower molecular weight siloxanes and odor forming products, often resulting in the loss of desirable functional groups and producing lower molecular weight siloxanes.
When these thiofunctional polysiloxane fluids are used in an electrostatic copying apparatus as a release agent to effect release between the toner treated paper which is impregnated with kaolin clays and a heated fuser roll the thiofunctional fluids have a tendency to degrade and form low molecular weight siloxanes and odor producing products. It is believed that this is caused by the kaolin clay which is present in the paper residue that collects in the sump along with the excess release agent and when the sump contents are reused the combination of acidic kaolin clay and the high temperature of the fuser roll causes the thiofunctional polysiloxane fluids to degrade to form volatile, low molecular weight siloxanes having reduced functional groups. Condensation of the low molecular weight volatile siloxanes on electrical switches can inhibit the switches function due to the good dielectric properties of the siloxanes.
Therefore, it is an object of this invention to provide a process for stabilizing thiofunctional polysiloxanes. Another object of this invention is to provide a process for stabilizing thiofunctional polysiloxanes against degradation in the presence of kaolin clays. A further object of this invention is to provide a process where thiofunctional polysiloxane fluids are rendered resistant to degradation in the presence of heat and kaolin clay without significantly affecting the properties of the thiofunctional polysiloxane fluids.